Portable Metal Detector with Remote Power Conversion for Low-Noise Sensing
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Solution Overview
Problem
Existing metal detectors face inefficiencies in power supply due to resistance in wired connections between power electronics and coils, leading to degraded coil power supply efficiency and interference with signal reception, especially when adjusting power levels.
Innovation Solution
A portable metal detector design with a power converter remotely located from the detection coil, allowing adjustable voltage adjustment and minimizing electromagnetic interference, using a battery and power converter offset from the coils to reduce signal disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If power electronics are placed close to the coil to reduce Joule losses, then power supply efficiency is improved, but electromagnetic interference with signal reception increases
Solution Approach 1:
The system is divided into two separate units: a detection disc containing the coil and positioned close to the ground for optimal signal reception, and a remote control box housing the power electronics including the switching voltage converter. This spatial segmentation allows the power electronics to be optimized for efficiency while being physically isolated from the sensitive coil to minimize electromagnetic interference with detected signals.
Solution Approach 2:
A long wire connection acts as an intermediary between the remote power electronics and the coil, enabling power delivery while providing electromagnetic isolation. The wire serves as a controlled impedance transmission line that delivers power over distance while the remote positioning of power electronics minimizes their electromagnetic interference with the sensitive detection signals.
2Power
If excitation current is increased to boost magnetic field power, then detection capability is improved, but power losses and excitation means oversizing increase
Solution Approach 1:
Instead of increasing excitation current to boost magnetic field power, the invention changes the operating parameter to high excitation voltage using a switching voltage converter in voltage boost configuration. This allows achieving the required magnetic field power while operating at lower currents, thereby reducing Joule losses and avoiding oversizing of the excitation means.
3Power
If switching voltage converter is used to increase excitation voltage, then magnetic field power is improved, but radiated electromagnetic noise increases
Solution Approach 1:
The switching voltage converter generating electromagnetic noise is extracted and positioned remotely in the control box, separated from the sensitive coil in the detection disc. This spatial extraction allows the noisy power conversion function to be performed while minimizing its electromagnetic interference with the sensitive signal detection, as the converter is physically removed from the immediate vicinity of the coil.
4Ease of manufacture
If wired connection is used between control box and coil, then power delivery is simplified, but resistance degrades power supply efficiency
Solution Approach 1:
The system dynamically optimizes the trade-off between wired and wireless power delivery by using wired connection for high-power excitation where efficiency is critical, while accepting the resistance limitation as a design constraint that drives the remote positioning of power electronics. The wired connection provides reliable power delivery while the system compensates for resistance losses through optimized power management and remote positioning.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances detection power while maintaining signal integrity by reducing electromagnetic interference and enabling efficient power supply without degrading signal quality.
Implementation Method 1
The electromagnetic coil is configured to generate an electromagnetic field that interacts with metal objects buried in a substrate such as the ground. The electromagnetic field induces electric currents in these metal objects
Implementation Method 2
a power converter which is electrically connected to the battery, this power converter is configured to produce a direct electric current whose voltage value is modified relative to the voltage value of the current at the terminals of the battery
Implementation Method 3
the resistance of a wire is proportional to its length and inversely proportional to its diameter. Thus, a long and small diameter electric wire produces a high resistance which degrades the power supply efficiency of the electromagnetic coil by Joule effect
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a portable metal detector (20) with increased detection power by the addition of a power converter (25). The power converter (25) is remote from the detection disc (22) and in particular from the member for capturing electrical disturbances of the electromagnetic field produced by the transmitting coil(s) (220). This remote location makes it possible in particular to prevent the working frequency of the power converter (25) from producing disturbances in the signal captured by the capture member.